[PATCH 5.10 405/406] drm/amd/display: Fix a bug when searching for insert_above_mpcc

Greg Kroah-Hartman
2023-09-17T19:43:24Z

From: Wesley Chalmers <wesley.chalmers@amd.com>

commit 3d028d5d60d516c536de1ddd3ebf3d55f3f8983b upstream.

[WHY]
Currently, when insert_plane is called with insert_above_mpcc
parameter that is equal to tree->opp_list, the function returns NULL.

[HOW]
Instead, the function should insert the plane at the top of the tree.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Wesley Chalmers <wesley.chalmers@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_mpc.c
@@ -206,8 +206,9 @@ struct mpcc *mpc1_insert_plane(
/* check insert_above_mpcc exist in tree->opp_list */
struct mpcc *temp_mpcc = tree->opp_list;

- while (temp_mpcc && temp_mpcc->mpcc_bot != insert_above_mpcc)
- temp_mpcc = temp_mpcc->mpcc_bot;
+ if (temp_mpcc != insert_above_mpcc)
+ while (temp_mpcc && temp_mpcc->mpcc_bot != insert_above_mpcc)
+ temp_mpcc = temp_mpcc->mpcc_bot;
if (temp_mpcc == NULL)
return NULL;
}